// SERVER-9841 $map expression to map over arrays
import {assertErrorCode} from "jstests/aggregation/extras/utils.js";

var t = db.server9841;
t.drop();
t.insert({
    simple: [1, 2, 3, 4],
    nested: [{a: 1}, {a: 2}],
    mixed: [{a: 1}, {}, {a: 2}, {a: null}],
    notArray: 1,
    null: null,
});

function test(expression, expected) {
    var result = t.aggregate({$project: {_id: 0, res: expression}}).toArray();
    assert.eq(result, [{res: expected}]);
}

test({$map: {input: "$simple", as: "var", in : '$$var'}}, [1, 2, 3, 4]);
test({$map: {input: "$simple", as: "var", in : {$add: [10, '$$var']}}}, [11, 12, 13, 14]);
test({$map: {input: "$simple", in : '$$this'}}, [1, 2, 3, 4]);

test({$map: {input: "$nested", as: "var", in : '$$var.a'}}, [1, 2]);
test({$map: {input: "$nested", as: "CURRENT", in : '$a'}}, [1, 2]);

test({$map: {input: "$mixed", as: "var", in : '$$var.a'}},
     [1, null, 2, null]);  // missing becomes null

test({$map: {input: "$null", as: "var", in : '$$var'}}, null);

// can't set ROOT
assertErrorCode(t,
                {$project: {a: {$map: {input: "$simple", as: "ROOT", in : '$$ROOT'}}}},
                ErrorCodes.FailedToParse);

// error on non-array
assertErrorCode(t, {$project: {a: {$map: {input: "$notArray", as: "var", in : '$$var'}}}}, 16883);

// parse errors (missing or extra fields)
assertErrorCode(
    t, {$project: {a: {$map: {x: 1, input: "$simple", as: "var", in : '$$var'}}}}, 16879);
assertErrorCode(t, {$project: {a: {$map: {as: "var", in : '$$var'}}}}, 16880);
assertErrorCode(t, {$project: {a: {$map: {input: "$simple", as: "var"}}}}, 16882);

// 'in' uses undefined variable name.
assertErrorCode(t, {$project: {a: {$map: {input: "$simple", in : '$$var'}}}}, 17276);